1. Field of the Invention
The present invention relates to a low-density cleaning substrate with a basis weight of less than 80 gsm, which may be expanded in the z-direction to give the consumer the appearance of additional perceived bulk and thickness. The present invention further relates to cleaning substrates that are preferably used as wipes for delivering cleaning, disinfecting and surface protective compositions to both hard and soft surfaces. The cleaning substrate may be a pre-loaded cleaning wipe preferably comprised of non-woven materials, which have an optimized pore volume distribution that allows the pre-loaded cleaning composition to be controllably released from the substrate.
2. Description of Related Art
A variety of liquid and solid or semi-solid ingredients have been deposited onto various forms of substrates for a variety of purposes. Typically, the substrates are wipes, formed of either a woven or non-woven material, and containing a liquid active composition. In one form, a non-woven material is soaked in a liquid cleaning active, and packaged in a canister. One example of this form of a disposable cleaning wipe is a product manufactured and sold by the Clorox Company under the trademark Clorox® Disinfecting Wipes.
Cleaning wipes have long been used for a variety of purposes. Such cleaning wipes have contained various compounds to accomplish their intended purpose. Cleaning wipes have included soaps and detergents to clean hard surfaces such as tiles, ceramics, counter tops, floors, and the like, as well soft surfaces such as fabrics and upholstery. Wipes have been formulated with personal care products, for example to clean an individual's hands. Cleaning wipes have also included ammonia to clean glass surfaces. Alcohol and various other biocides, such as quats, and biguanides have been included on cleaning wipes to disinfect a variety of surfaces. Cleaning wipes have also included waxes to polish and clean furniture.
All of the foregoing examples are limited in at least one or more of the following ways. First, many of the wipes or substrates have a basis weight of 45 to 80 gsm or more because higher basis weight substrates are customarily used because of their ability to effectively absorb and hold cleaning compositions. Secondly, many of the existing wipes are flat and consumers have traditionally rejected flat, low basis weight cleaning wipes and substrates because they appear too flimsy or thin to effectively clean surfaces. Thirdly, many of the existing cleaning substrates are geared toward maximizing absorption capacity and are not designed to controllably release a pre-loaded cleaning composition.
U.S. Pat. No. 4,042,453 to Conway, et al. is directed to a tufted non-woven water-laid fibrous web with high bulk and absorbency. The tufted non-woven webs described by Conway may be produced at basis weights as low as 0.5 ounces per square yard (osy) but most materials are at least 1 osy or higher. This patent discloses a tufting process for non-woven substrates, which increases absorbency and softness and creates the appearance of bulk even at low basis weights. Since this invention is focused on increasing absorption capacity, it is limited to tufted non-woven webs that quickly absorb fluids rather than non-wovens, which slowly and controllably release fluids.
U.S. Pat. No. 5,650,214 to Anderson, et al. describes a soft, elastic-like web material with raised rib texture patterns. This patent refers to a wide variety of methods for forming textured webs including thermoforming, applying high-pressure plates or rolls, hydraulic forming, casting and embossing. This patent teaches webs that are capable of exhibiting “elastic-like” behavior without the need for more expensive traditional elastomeric materials. The patent is limited in that it requires that the web material contain elastomeric materials that enable the web to stretch and deform along at least one axis. Therefore, this patent does not teach or direct use of textured web materials outside the area of elastic-like applications.
U.S. Pat. No. 6,172,276 to Hetzler, et al. describes an absorbent, low-density web material used for personal care products. To maximize absorbency of menses this patent teaches that the web should have a pore size distribution where more than 50 percent of the pore diameters are between 80 and 400 microns, as measured by a receding liquid. This reference teaches that in low-density substrates a high percentage of large pore sizes are beneficial for wicking and absorbency, but uses only receding liquid curves without any mention of the significance of advancing liquid curves or the relative importance between the two curves. Furthermore, the claims are directed to the percentage of pores with diameters between 80 and 400 microns and not the percentage of cumulative volume held in specific pore sizes. This patent is limited to a personal care product for absorbing menses and with more than 50 percent of the pores diameters are between 80 and 400 microns.
U.S. Patent Application Publication No. 2004/0131820 relates to tufted fibrous webs with discontinuous portions defining a longitudinal axis. The patent further describes the fibrous webs as being formed from spunbond or meltblown fibers with basis weights any where in the range of 10 to 500 gsm. The application is limited to webs with asymmetrical deformations having a longitudinal axis that are absorbent or non-absorbent, but not substrates capable of controllably releasing fluids.
United States Patent Application Publication No. 2003/0203162 to Fenwick, et al. describes a process for creating a non-woven fabric using three-dimensional surface features that are air permeable. The non-woven fabric of the invention has a basis weight from 3 to 400 gsm. The non-woven material of the application is primarily directed toward personal care products and is limited because it requires that it be made using a three-dimensional surface with features that are air permeable.
United States Patent Application Publication No. 2003/00118816 to Polanco, et al. describes a high loft, low-density non-woven web with a basis weight of 0.3 to 25 osy. This patent application requires that the non-woven web have spunbond, crimped bicomponent fibers of A/B side-by-side morphology. In addition, the non-woven material of this application is designed for its fast wicking and absorption capacity rather than its ability to controllably release fluids.
PCT Patent Publication No. WO2004/098869 to Pourdeyhimi et al. describes three-dimensional molded non-woven materials that comprise thermoplastic components to make the substrate more rigid and stiff. This reference teaches three-dimensional non-woven materials that have basis weights in the range of 90 to 350 gsm and are designed to act as sturdy compression supports. Therefore this reference does not disclose three-dimensional non-woven substrates with low basis weights.
European Patent Publication No. WO/0066057 to White et al. describes a method of manufacturing non-woven materials having surface features and the materials produced thereby. This publication describes forming non-woven materials into a three-dimensional non-woven web and coating the web with raised ridges. The non-woven materials may have low basis weights of about 0.25 to 50 osy. This publication is limited to absorbent, non-woven webs with continuous fibers having ridges and does not describe or suggest non-woven low basis weight substrates, which are capable of controllably releasing fluids.
European Patent No. 0664842 to Milligan describes a meltblown non-woven web formed with thermoplastic polymer fibers. The meltblown non-woven web has a low packing density and is air permeable because it is generally used for filtration devices. The patent is limited to meltblown non-woven materials with thermoplastic fibers.
In view of the present state of the art of non-woven substrates such as cleaning wipes, there remains a need for a low-density non-woven substrate that may be expanded in the z-direction and has the majority of the cumulative pore volume contained in a specific pore size range so that it is capable of controllably releasing a cleaning composition.